<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>inline-block</title>
    <style>
      * {
        margin: 0;
        padding: 0;
      }
      .container {
        background-color: navajowhite;
      }
      .left {
        background-color: red;
      }
      .right {
        background-color: blueviolet;
      }

      .container {
        display: table;
      }
      .left {
        display: table-cell;
        width: 300px;
      }
      .right {
        display: table-cell;
        width: calc(100vw - 300px);
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="left">
        this is left
      </div>
      <div class="right">
        this is right
      </div>
    </div>
  </body>
</html>
